A method for locating, measuring and evaluating the enlargement of a foramen are provided. An instrument has a handle, an angled region, and a tip to be inserted into the foramen. An instrument can be pressed onto the foramen to determine its location and whether the empty space within the foramen is large enough for the maximum width of the tip to be inserted. If the tip cannot insert, the foramen can be cut to enlarge it enough for the tip to insert. A kit of several instruments or a single instrument with tips of different maximum widths are provided for determining the amount of empty space within the foramen through the course of the enlargement.